Key Takeaways

Black coffee in the morning does not appear to signal the start of the eating window

But you absolutely cannot put cream/sugar in it and still be in a fasted state

Mouse studies show that time-restricted eating leads to weight loss (specifically coming from a loss of body fat)

A sleep deprived brain tricks us into thinking we’re hungrier than we actually are, and hinders our decision making ability when it comes to food (what to eat/when to stop eating/how much to eat)

Sleep deprivation, in combination with late night eating, is very problematic

During sleep we produce growth hormone that help repair damaged cells – When we sleep less, we have less of this growth hormone present to repair our cells

When we eat late into the night, our stomach is thus working late into the night to digest the food – so the stomach cannot repair itself

Lack of growth hormone, in conjunction with food in the stomach, slows down the repair process

This causes damage in the gut which can accumulate

When the gut lining is damaged – allergy causing food particles or disease causing bacteria can enter the blood and cause more inflammation

And MANY chronic diseases, have their root in increased inflammation

You probably aren’t really a night owl – you just have too much caffeine late in the day, and expose yourself to too much blue light too close to bedtime

Shift work is VERY unhealthy because it disrupts your circadian rhythm

Shift workers are at a very high risk for colon cancer

From user data from Satchin’s app, called My Circadian Clock, Satchin has found that many people, while practicing time-restricted eating, see an improvement in acid reflux, as well as an improvement in sleep

Satchin eats his last meal at around 6pm

Intro

Dr. Satchin Panda (@SatchinPanda) is a professor and researcher at the Salk Institute who has become recognized as one of the world’s leading experts on circadian rhythm

Check out the Podcast Notes from Satchin’s appearance on Found My Fitness with Dr. Rhonda Patrick

The Early Days

The large lifestyle difference between Satchin’s grandfathers:

Satchin’s maternal grandfather worked on the Indian railway, often during the night shift

Years later, after retiring, Satchin’s maternal grandfather developed Alzheimer’s disease and passed away in his early 70s

As a contrast, his paternal grandfather worked on a farm, with no electricity

He lived up until his early 90s with no cognitive impairments

“This really surprised me, how these two different lifestyles, led to a very different outcome”

When he was only 13, Satchin lost his father in a road accident – he was killed by a truck driver who was very sleep deprived

Satchin notes how it’s illegal to drive when you’re drunk, and there ways to measure how much alcohol you have in your blood

BUT – “We know that being sleep deprived is almost as dangerous or even more dangerous than driving drunk”

Why isn’t it illegal to drive when you’re sleep deprived?

We have no way to measure whether someone is sleep deprived

Time-Restricted Feeding – Part 1

In Satchin’s first time restricted feeding mouse study, he took mice from the same mother, identical in age and gender, and fed 1 group an around the clock high fat/high sucrose diet, and the other group the same diet, but with a limited 8 hour eating window

Both groups ate the same number of calories

60% of their calories were from fat, 20% from sucrose, and the rest from protein

After 18 weeks, it was found that the mice who followed the 8 hour eating window, weighed 28% less on average

Satchin repeated this experiment 3 times, with similar results each time

Time restricted eating and ketosis

After 12-16 hours without food, blood ketone levels begin to rise

After ~10 hours, ketone levels begin to rise in the cells that produce them

In another ~4 hours, you see a rise in the ketone levels in your blood

“Some of the health benefits of time restricted feeding, may be mediated by this increase in ketone bodies”

Endurance

The mice that followed the time-restricted eating window in the above study, showed an increase in endurance

This is thought to originate from the presence of ketone bodies in the blood

What signals the start of the eating window?

Black coffee is fine in the morning – it does not signal the part of the eating window

BUT you CANNOT put cream and sugar in it

Obesity and Time-Restricted Eating

In one study, Satchin took obese mice, and had them follow a 9 hour time-restricted feeding diet

Over the next 13 weeks, the mice lost a large amount of fat (not muscle), and improved their glucose tolerance (this is a good thing)

Almost two thirds of the U.S. population is overweight or obese – more people should be restricting their eating windows

Sleep and the Dangers of Shift Work

Shift work is unhealthy because it disrupts your circadian rhythm

Shift work can be defined as “staying awake for 3 hours (or more) between 10pm and 5am, for at least once a week”

In that sense – “Almost everyone is a shift worker”

A sleep deprived brain:

Tricks us into thinking we’re more hungry – it miscalculates how much energy we really need for the rest of the day (causing you to eat more)

Makes bad decisions about food

In a typical day we make ~250 different decisions about our food alone (when to eat, what to eat, how much to eat etc.)

So we’re overeating the wrong things

Sleep deprivation, in combination with late night eating, causes more damage

During sleep we produce growth hormone that help repair damaged cells

When we sleep less, we have less of this growth hormone present to repair our cells

When we eat late into the night, our stomach is thus working late into the night to digest the food – so the stomach cannot repair itself

Lack of growth hormone, in conjunction with food in the stomach, slows down the repair process

This causes damage in the gut which can accumulate

When the gut lining is damaged – allergy causing food particles or disease causing bacteria can enter the blood and cause more inflammation

The WHO has recently classified shift work as a potential carcinogen

Shift workers are at a very high risk for colon cancer

This is because they tend to eat late into the night, and have altered circadian rhythms – never really giving the gut the rest it needs

Chronotypes

This is the term for when you prefer to be awake (night owl vs. a morning lark)

The problem is, that most people force themselves to be night owls, either by drinking coffee too late in the day, or by exposing themselves to too much light close to bed time

The Importance of Darkness

“In modern society, we’ve lost our right to darkness”

In our retinas, we have a blue light sensing protein called melanopsin present in ~5,000 cells

These proteins sense the blue spectrum of light

These cells, which contain melanopsin, are hard wired to the master circadian clock neurons in our brain

They’re also directly connected to meltaonin producing cells in the pineal gland

So exposure to blue light (by watching TV, or staring at your phone, or walking around in a brightly lit grocery store) reduces the amount of melatonin that your brain is producing, for several hours

“As we are exposed to more light, we are likely to sleep less, and likely to make many more bad decisions like eating late at night, and eating unhealthy food”

Why do we need a strong eating/fasting rhythm, and a strong sleep/work cycle?

Just like your brain has to sleep to reset/repair/rejuvenate for another day, every organ in our body needs down time to repair and reset

“When your organs are repaired and rejuvenated, it’s almost like taking care of your car, getting the oil changed and tires rotated, on a daily basis”

Our circadian clock allows this to happen by:

Exposing us to light/darkness for defined intervals (sleep is essentially just darkness)

By producing hunger and satiety signals – so we’re in the “not hungry” stage for 12 hours or more per day

By obeying these hunger/satiety signals, we can give our organs the time they need for repair/rejuvenate

Most diseases are due to a lack of repair

When our gut is not repaired well (caused by eating late into the night), leaky gut can develop

This can lead to allergy causing chemicals entering the body, or disease causing bacteria entering the blood stream (thus causing inflammation)

MANY chronic diseases, have their root in increased inflammation

Our gut lining recycles every 10-15 days – so we have a new layer of cells every 10-15 days in our gut lining

Each one of us has genes that will predispose us to one or more diseases

Satchin took mice who “lacked an internal clock” (caused by a lack of certain genes)

Because of this, the brains of these mice could not tell when to start/stop eating – this predisposes them to obesity

They were then forced to follow a time-restricted eating regimen

The mice were found to be “as healthy” as mice who have an internal clock, despite being predisposed to metabolic syndrome/obesity

Many humans have mutations in internal clock regulating genes, or mutations in melatonin receptor genes (thus altering how we feel the affects of melatonin) – Satchin estimates about 30-40% of the population

These people are at a high risk of obesity, type 2 diabetes, and certain cardiovascular diseases

Satchin’s mouse study, points to the fact that a time-restricted eating regimen might be able to override their predisposition to obesity

Human Time-Restricted Eating Study

Satchin describes a study out of the University of Alabama, which came out in 2018

Two groups of humans were examined

Both groups consumed the same number of calories

One group restricted their eating window to 6 hours, and the other for 12 hours